Advances in semi-conductor processing and logic design have permitted an increase in the amount of logic that may be present on integrated circuit devices. As a result, computer system configurations have evolved from single or multiple integrated circuits in a system to multiple hardware threads, multiple cores, multiple devices, and/or complete systems on individual integrated circuits. Additionally, as the density of integrated circuits has grown, the power requirements for computing systems (from embedded systems to servers) have also escalated. Furthermore, software inefficiencies, and its requirements of hardware, have also caused an increase in computing device energy consumption. In fact, some studies indicate that computing devices consume a sizeable percentage of the entire electricity supply for a country, such as the United States of America. As a result, there is a vital need for energy efficiency and conservation associated with integrated circuits. These needs will increase as servers, desktop computers, notebooks, ultrabooks, tablets, mobile phones, processors, embedded systems, etc. become even more prevalent (from inclusion in the typical computer, automobiles, and televisions to biotechnology).
A current ramp, i.e., a rapid change in the current drawn by a circuit, can cause a temporary spike or droop in the supply voltage drawn from a voltage regulator due to the impedances in the circuit. For example, an increase in the current drawn (i.e. an upward current ramp) may cause a droop in the voltage supplied by the voltage regulator, while a decrease in the current drawn (i.e. a downward current ramp) may be reflected as a spike in the supply voltage. A droop in the local supply voltage can slow down logic elements, potentially causing failures. Moreover, the voltage droop may be coupled back to the input of the voltage regulator, causing other circuits on a chip to fail.